MUSEUM OF NATURE

Press, Volume CVIII, Issue 31772, 31 August 1968, Page 5

MUSEUM OF NATURE

Neither Caterpillar Nor Worm

(Contributed by the Canterbury Museum)

Though many New Zealanders have probably encountered a peripatus when fossicking in the bush, it passes to all but the keenest gaze as “merely another caterpillar.”

However, caterpillar it is not: nor legged worm, nor centipede, nor slug—though biologists at various times have classified it as all of these creatures. Peripatus is so unusual that biologists have given up the task of trying to fit it into one of the closest animal groups and placed it in a special group all of its own. In this position it remains evidence of a some-time link between “worms" and “insects."

, Under a magnifying glass, peripatus resembles a miche-lin-tyre man of the caterpillar world. Its soft, thin, velvety skin is thrown into numerous wrinkles and each of its legs is a bulgy cylinder and terminates in a pair of tiny hooks. The large number of legs in peripatus indicates that it cannot possibly be a

caterpillar. Fourteen to fortytwo pairs (according to species) is rather more reminiscent of centipedes and millipedes; but without these creatures’ harder, jointed, outer skeleton. Very Old There are about 80 different kinds of peripatus, found mainly in warmer parts of the world: the West Indies; Central and South America; South Africa and the Indo-Australasian regions. Geologically, or rather palaeontologically speaking, they are very ancient, their relations having graced Cambrian seas about 500 million years ago.

Peripatus today lives only on land, lurking in rotten logs, under stones, under bark—in places that are always damp and always away from the light. Dampness is critical to peripatus. Without moisture it will quickly dry out, losing all its internal moisture through minute breathing holes which are scattered all over the skin. Unlike insects, peripatus cannot open and close these breathing holes and therefore cannot control water loss. Experiments have shown that peripatus will dry out 40 times as fast as a caterpillar and 80 times as fast as a cockroach if all three are placed in the same humidity.

An adult peripatus grows to about 2in to 2jin in New Zealand. It comes in several colours: brownish, deep bluegreen or slate-blue, and is often ornamented by a variety of orange, blue or green spots. Though many-footed, it moves rather slowly in a bewildered way, occasionally raising itself caterpillar fashion to test the surrounding air or moist ground and foliage. It feeds on small insects and other minute creatures of the hidden world of the underlog. Undoubtedly its greatest achievement and best defence lies in its ability to spit—a skill which for its size even the renowed Llama beast would find Impossible to equal. The spit is sticky and produced in enormous glands inside the animal that extend almost the full length of the body. Biologists consider that the peripatus does not use this elastic sticky mucus to catch its food, but simply to entangle a potential enemy. And though the texts state 12in as the distance the peripatus is able to eject the mucus, 1 feel sure that many a New Zealand naturalist would vouch for considerably greater distances as a result of personal encounters. — M.M.D. and J.T.D.

The photograph shows the New Zealand peripatus, found in a rotten log in native bush.